Optical storage medium having multiple recording layers of different formats

ABSTRACT

A disc recording medium has recorded thereon a first program in a first recording area and corresponding first management data for managing readout of the first program and providing information, such as track number and play time, to the user. The disc recording medium also has a second program recorded in a second recording area and corresponding second management data for managing readout of the second program. The second management data includes only an absolute time code and track start time codes, but no track numbers or play times, and the track numbers are derived using the second management data.

This is a division of prior application Ser. No. 09/397,808 filed Sep.17, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a reproduction method and also to areproduction apparatus adapted to transmit a first digital signal formain data of a piece of music and additional data accompanying the maindata and including the number of the piece of music and the elapsed timeon the track and a second digital signal for main data of the piece ofmusic and accompanying absolute time data on a common digital interface.

2. Related Background Art

The digital audio interface output of known compact disk (CD) players isadapted to produce, in addition to main data that are digital audiodata, channel status data including a category code for identifying theCD category of the CD disk to be played and user data comprising Qcodes, each including a track number and the elapsed time of a piece ofmusic on the track.

On the other hand, many known digital recording apparatus using adigital audio tape (DAT) or a mini-disk (MD) as recording medium aredesigned to automatically record start IDs and track numbers on therecording medium for a great convenience of the user on the basis of theCD category identified by decoding the channel status data and thesub-data including the track numbers and the elapsed time of each pieceof music recorded on the CD to be replayed as detected by decoding the Qcode of the user data when receiving data from the CD player by way ofthe digital audio interface.

Meanwhile, in recent years, standards for optical disks that aredifferent from known CDs and adapted to record high speed 1-bit digitalaudio signals for music have been proposed. Audio data addressed by theproposed standards are 1-bit audio signals obtained by subjectingcorresponding analog audio signals to a delta-sigma (ΔΣ) modulationprocess. A 1-bit audio signal is sampled with a very high samplingfrequency that is 64 times as high as the sampling frequency of 44.1 KHzof ordinary CDs. The signal is expressed in terms of a very highsampling frequency and a data word length with a very small number ofquantization bits and hence characterized by a wide transmissionfrequency band. Additionally, due to the ΔΣ modulation, it can secure awide dynamic range in the audio band that is a low frequency bandrelative to the over-sampling frequency that is 64 times as high as thesampling frequency of ordinary CDs.

An optical disk deals with high speed 1-bit audio signals conforming tothe proposed standards for new digital audio signals and shows audiocharacteristics by far more excellent than those of known CDs. However,a recording system totally different from that of known CDs has to beused for it and hence is not compatible with known CDs in terms ofinformation on the track numbers and the elapsed time of each piece ofmusic as contained in the sub-data as well as other data.

Therefore, when producing a digital audio interface output in a diskreplaying apparatus adapted to digital audio signals conforming to theproposed new standards, the category code of the channel status data,the user data and other data generally have to be newly defined andmanaged.

However, the use of such newly defined data is totally detrimental tothe above identified convenience of recording start Ids and tracknumbers on the recording medium when the data are recorded by way of thedigital interface to a known digital recording apparatus.

Particularly, with a reproduction apparatus adapted to both digitalaudio disks conforming to the new standards and existing CDs, therearises a confusing situation where the above convenience is availablewhen replaying with a CD whereas it is not available when replaying anew disk to a great inconvenience on the part of the user of theapparatus.

SUMMARY OF THE INVENTION

In view of the above identified circumstances, it is therefore an objectof the present invention to provide a reproduction method and areproduction apparatus adapted to use channel status data and user datain the format equivalent to that of CDs for the digital audio interfaceoutput when replaying a disk for digital audio signals recorded with asystem different from that of CDs so that the convenience ofautomatically recording starts Ids and track numbers on the digitalrecording medium such as DAT or mini-disk can be ensured as in the caseof a CD.

Another object of the present invention is to provide a reproductionapparatus and a reproduction method adapted to use channel status dataand user data in the format equivalent to that of CDs for the digitalaudio interface output particularly in the case of a reproductionapparatus adapted to both digital audio disks conforming to the newstandards and existing CDs.

According to an aspect of the invention, the above objects are achievedby providing a reproduction apparatus adapted to selectively replaying afirst recording medium having a program area storing a plurality ofprograms formatted according to a first format and sub-data including atleast the passed-by addresses of each program and the program numbers;and

a second recording medium having a program area storing a plurality ofprograms formatted according to a second format different from saidfirst format and sub-data accompanying said programs and includingabsolute addresses and a control area for controlling recordingaddresses expressed in terms of absolute addresses and corresponding theprograms stored in said program area;

said reproduction apparatus comprising:

a reproduction means for replaying the control area and the program areaof said second recording medium;

a memory means for storing recording addresses expressed in terms ofabsolute addresses and corresponding to the programs recorded in thecontrol area of said second recording medium and replayed by saidreproduction means;

a sub-data generation means for generating the program number and thepassed-by addresses of the program currently being reproduced on thebasis of the absolute addresses reproduced from the program area of saidsecond recording medium by the recording addresses as expressed in termsof absolute addresses and corresponding to the programs stored in saidmemory means and also by said reproduction means; and

an interface output means for receiving as input the passed-by addressesand the program number of each of the programs reproduced from theprogram area of said first recording medium when replaying said firstrecording medium and receiving the passed-by addresses and the programnumber of the program currently being reproduced as generated by saidsub-data generation means, transforming them and outputting them to apredetermined digital interface when replaying said second recordingmedium.

According to another aspect of the invention, there is provided areproduction apparatus adapted to selectively replaying a first layerhaving a program area storing a plurality of programs formattedaccording to a first format and sub-data including at least thepassed-by addresses of each program and the program numbers and a secondlayer having a program area storing a plurality of programs formattedaccording to a second format different from said first format andsub-data accompanying said programs and including absolute addresses anda control area for controlling recording addresses expressed in terms ofabsolute addresses and corresponding the programs stored in said programarea;

said reproduction apparatus comprising:

a reproduction means for selectively replaying the program area of saidfirst layer and the control area and the program area of said secondlayer;

a memory means for storing recording addresses expressed in terms ofabsolute addresses and corresponding to the programs recorded in thecontrol area of said second layer and replayed by said reproductionmeans;

a sub-data generation means for generating the program number and thepassed by addresses of the program currently being reproduced on thebasis of the absolute addresses reproduced from the program area of saidsecond layer by the recording addresses as expressed in terms ofabsolute addresses and corresponding to the programs stored in saidmemory means and also by said reproduction means; and

an interface output means for receiving as input the passed-by addressesand the program number of each of the programs reproduced from theprogram area of said first layer when replaying said first layer andreceiving the passed-by addresses and the program number of the programcurrently being reproduced as generated by said sub-data generationmeans, transforming them and outputting them to a predetermined digitalinterface when replaying said second layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a disk replaying apparatusembodied according to the invention.

FIG. 2 is a schematic illustration of the data structure of a sub-codingframe format applicable to known CDs.

FIG. 3 is a schematic illustration of the frame data structure of a Qdata applicable to known CDs.

FIG. 4 is a schematic illustration of the frame data structure of a Qdata in a program area applicable to known CDs.

FIG. 5 is a schematic illustration of the data structure of a sub-frameconforming to the Digital Audio Interface Standards.

FIG. 6 is a schematic illustration of the data structure of a frameconforming to the Digital Audio Interface Standards.

FIG. 7 is a schematic illustration of the data structure of channelstatus data.

FIG. 8 is a schematic illustration of the data structure of user datawhen the category of channel status data indicates the CD category.

FIG. 9 is a schematic illustration of the data structure when asub-frame conforming to the Digital Audio Interface Standards is used asuser data.

FIG. 10 is a schematic illustration of the data structure when asub-frame conforming to the Digital Audio Interface Standards is used aschannel status data.

FIG. 11A is a schematic illustration of the data structure of an HD diskapplicable to the present invention.

FIG. 11B is a detailed illustration of the data structure of area TOCshown in FIG. 11A.

FIG. 11C is a detailed illustration of the data structure of the trackarea shown in FIG. 11A.

FIG. 11D is a detailed illustration of the data structure of each trackof the track area shown in FIG. 11A.

FIG. 12 is an illustration of the data table that may be recorded in thetrack list in an area TOC data.

FIG. 13 is an illustration of the data table that may be recorded in theindex list in an area TOC data.

FIG. 14 is an illustration of the data table of an audio header in theaudio sector of each track.

FIG. 15 is an illustration of the data table of frame info in the audioheader of each track.

FIG. 16 is a specific example of table of the track list and the indexlist in an area TOC data.

FIG. 17 is a schematic illustration of the data structure of asub-Q-data.

FIG. 18 is a flow chart of the operation of generating track numbers,index numbers and elapsed time that can be used for the purpose of theinvention.

FIG. 19 is a schematic illustration of the data structure indicatingtrack numbers, index numbers and start times that can be actuallygenerated on the basis of the table of FIG. 16.

FIG. 20 is a flow chart of the processing procedure according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described by referring to theaccompanying drawings that illustrate preferred embodiments ofreproduction apparatus and reproduction method according to theinvention.

The embodiment of reproduction apparatus according to the invention asdescribed hereinafter is adapted to replay music from a compact disk(CD) and also from a novel optical disk storing high speed 1-bit digitalaudio signals and also output audio signals conforming to the DigitalAudio Interface Standards. An optical disk of the new type storing highspeed 1-bit digital audio signals will be referred to as an HD (highdefinition) disk hereinafter.

Each high-speed 1-bit audio signal recorded on an HD disk is obtained bymeans of delta-sigma (ΔΣ) modulation of an analog audio signal and has adata format of a data word length of 1-bit and a sampling frequency of2,8224 MHz (44.1 KHz×64).

FIG. 1 is a schematic block diagram of disk replaying apparatus 1embodied according to the invention.

Referring to FIG. 1, optical disk 2 is a multilayer disk comprising afirst layer storing multi-bit digital audio signals in the conventionalCD format and a second layer storing 1-bit digital audio signals in thenew format referred to as the HD format.

In a different mode of carrying out the invention, a reproductionapparatus may be so arranged as to selectively carry and drive aconventional CD or another device storing 1-bit digital audio signals inthe HD format.

The signal read out from the optical disk 2 by means of optical pickup 3is input to physical signal detector/processor 5 by way of RF amplifier4.

In the case where the optical disk 2 is an HD disk or an HD layer, thephysical signal detector/processor 5 carries out an operation ofphysically processing the signal including EFM plus demodulation,product coding and descrambling and transmits a 1-bit delta-sigmamodulated digital audio signal having a sampling frequency of fsmultiplied by 64 (64×44 KHz=2.8224 MHz) to audio signal processor 6 andadditional information detector/processor 8.

On the other hand, in the case where the optical disk 2 is a CD, thephysical signal detector/processor 5 carries out an operation ofphysically processing the signal including EFM demodulating and CIRC(cross interleaved Reed-Solomon coding) and transmits a digital audiosignal sampled with a sampling frequency of fs (44.1 KHz) and having aquantization bit number of 16 bits to audio signal processor 11 andadditional information detector/processor 12.

The audio signal processor 6 demodulates the 1-bit digital audio signalthat is reproduced from the optical disk 2 and sampled with the samplingfrequency of fs multiplied by 64 (64×44.1 KHz=2.8224 MHz) and the rateconverter 13 down-converts the 1-bit digital audio signal sampled withthe sampling frequency fs multiplied by 64 (64×44.1 KHz=2.8224 MHz) to amulti-bit digital audio signal having a sampling frequency of f2 (44.1KHz) and a quantization bit number of 16 bits that are equivalent withthose of a CD and transmits it to one of the terminals of first switch14.

On the other hand, the additional information detector/processor 11demodulates the digital audio signal having a quantization bit number of16 bits that is reproduced from the optical disk 2 and sampled with thesampling frequency of fs (44.1 KHz) and transmits to the other terminalof the first switch 14.

Then, the multi-bit digital audio signal selected by the first switch 14is fed to interface output section 7.

The digital audio interface output section 7 outputs the multi-bitdigital signal typically as digital audio interface output conforming tothe IEC958 format.

The additional information detector/processor 8 separates all theinformation other than the audio signal from the data string containingsaid 1-bit digital audio signal. More specifically, it detects timeinformation TCP, which will be described hereinafter, from the headerinformation contained in said data string and transmits it to sub-dataconverter/generator 9. Additionally, it extracts information on thestart time of each track and that of each index such as track start timecodes and index start time codes from the control information arrangedat the head and the trail of said data string and stores the extractedinformation in memory 10.

The sub-data converter/generator 9 converts and generates sub-data suchas channel status data and user data that conform to the DigitalInterface Standards on CDs by means of said time information TCP fedfrom the additional information detector/processor and said track starttime information and index start time information stored in said memory10.

The sub-data generates by the sub-data converter/generator 9 such aschannel status data and user data to one of the terminals of secondswitch 15.

On the other hand, the additional information detector/processor 12separates all the information other than the audio signal from the datastring containing said multi-bit digital audio signal. Additionally, itextracts information conforming to the Digital Interface Standards onCDs such as channel status data and user data and transmits it to theother terminal of switch 15.

Then, the sub-data such as channel status data and user data selected bysaid switch 15 are transmitted to said digital audio interface outputsection 7 and synthetically combined with the multi-bit digital audiosignal from the audio signal processor 6 or the audio signal processor11. Then, it outputs the obtained data conforming to the Digital AudioInterface Standards to digital output terminal 1.

The first switch 14 and the second switch 15 are controlled for theirswitching operations by a control signal output from the control section16 on the basis of the outcome of the operation of determining if a CDor an HD or if a CD layer or an HD layer, whichever appropriate, is tobe handled.

Now, sub-data, or channel status data and user data conforming to the CDStandards, that can be converted and generated by the sub-dataconverter/generator 10 by means of the additional information extractedfrom the 1-bit digital audio signals from the optical disk 2 will bediscussed hereinafter.

According to the CD Standards, there are sub-data (P, Q, R, S, T, U, V,W) formed on a frame by frame basis that can be read out when the diskis driven for ordinary replay on a track by track basis. FIG. 2 is aschematic illustration of the data structure of a sub-coding frameformat of a compact disk audio system (conforming to the IEC(International Electro-technical Commission) 908 Standard). Sub-data Pthrough W are contained in each frame by 98 bits including sync bits S₀and S₁ for a sync pattern. P represents information on the intervalbetween two pieces on a track and R through W represent information onstill pictures and characters. Q represents most of the informationconverted and generated by the additional information detector/processor9 including track numbers and the elapsed time on each of the tracks aswell as the absolute time (minute, second, frame).

FIG. 3 shows a format applicable to a Q code. The 96 bits other than thesync bits of S₀ and S₁ include 4 CONTROL bits indicating the presence orabsence of emphasis and if copying the piece is permitted or prohibited,4 address (ADR) bits indicating the data mode, 72 Q data bits and 16cyclic redundancy check (CRC) bits for the generation of parity checkcodes. The number of address (ADR) bits will be reduced to 1 when thedata in the program area are being reproduced.

FIG. 4 is a schematic illustration of the frame data structure of a Qdata including only an address (ADR) bit. It includes track no TNO,index number X, the elapsed time on the track (minute (MIN), second(SEC), frame (FRAME)), the absolute time (minute (AMIN), second (ASEC),frame (AFRAME) from the head of the disk and CRC. Note that the elapsedtime on the track is that of a track with a specific track number.

FIG. 5 is a schematic illustration of the data format of a sub-frameconforming to the Digital Audio Interface Standards (IEC 958 Standards).FIG. 6 is a schematic illustration of the data structure of a framecontaining sub-frames as shown in FIG. 5.

The synchronization preamble (Sync Preamble), user data (U bit), channelstatus data (C-bit) and other data exist in each frame in addition toaudio data for the left and right channels.

FIG. 7 is a schematic illustration of the data format of channel statusdata. The data contains a category code for identifying the type ofapparatus, the sampling frequency fs and CONTROL bits for indicating thepresence or absence of emphasis.

FIG. 8 is a schematic illustration of the data format of a user datawhen the category code of FIG. 7 is “10000000”, indicating that thesignal source is a CD reproduction apparatus. Here, codes Q through Ware listed to exclude P code and, particularly, the 96 bits Q code willbe extracted therefrom.

FIG. 9 and FIG. 10 show examples of data including user data (U) andchannel status data (C) that can be actually output along with audiodata.

Thus, as described above, a digital output of a CD player containschannel status data indicating the CD category and user data indicatingthe track number and the elapsed time of the track.

On the other hand, according to the above described newly establishedstandards for optical disks (typically referred to as Super Audio CDStandards), a start address that corresponds to the absolute time of thestart of a track in the audio area is written in Track_List_2 in thearea TOC data. Only the time code contained in the initial header ofeach audio sector that corresponds to the absolute time of the start canbe read out during an ordinary operation of reproducing data from atrack.

FIG. 11A is a schematic illustration of the data structure of the audioarea on an optical disk conforming to the Standards, where each of thetwo area TOCs arranged on the opposite sides of the track area has aconfiguration as shown in FIG. 11B. Track_Start_Time_Code of each trackis described in Track_List_2 in the area TOC as shown in the syntax ofFIG. 12. Index start time code Index_Start_TC of each index number asshown in the syntax of FIG. 13 is described in Index_List of FIG. 11B.

On the other hand, Audio Sector as shown in FIG. 11D is provided on eachtrack as shown in FIG. 11C in the track area of FIG. 11A and Frame_Infoas shown in the syntax of FIG. 14 is described in Audio Header in theAudio Sector. More specifically, Time_Code of each frame is describedthere as shown in FIG. 15.

As described above, according to the HD standards, only the time code(absolute time) of each frame can be read out from a track area that isa program area during an ordinary operation of reproducing data from atrack unlike the CD format. In other words, information such as tracknumbers and the elapsed time of each track is not recorded. Therefore,it is not possible to display track numbers and the elapsed time of eachtrack.

In order to overcome this inconvenience, the disk replaying apparatus 1frrstly reads out area TOC (Table of Contents) data and stores it inmemory 8 as shown in FIG. 1 when a disk is placed in position. Thus, thememory 8 stores a table of TRACK LIST 2 and INDEX LIST as shown in FIG.16.

For driving the optical disk 2 for data reproduction and adding userdata (U bit) to its digital output, Q data as shown in FIG. 17 has to beproduced by additional information detector/processor 9 through a dataconversion/generation process.

Now, a conversion processing operation of a sub-data will be describedby referring to FIG. 18. Firstly, the time code (absolute time) of theaudio header has to be read out as TCP for each frame while th_e opticaldisk 2 is driven for data reproduction. Then, in Step S1, the absolutetime TCA (minute M, second S, frame F) of the TCP is written as shown inFIG. 17.

Then, in Step S2, Track_Start_Time_Code (TC2) of Track No. 2 (TNO 2) iscompared with the above TCP. If TCP is smaller than TC2, the operationproceeds to Step S3, where the current track number is specified as TNO1. In Step S4, TC1 of Track Number 1 (TNO. 1) is subtracted from the TCPto produce elapsed time TCN (minute, second, frame).

After Step S4, the operation proceeds to the processing sequence of *1surrounded by broken lines in FIG. 18, where the index number (IDX) inthe track number TNO 1 is determined.

In Step S5, Index_Start_TC of INDEX 2 of the track number TNO. 1 inIndex_List is compared with the above TCP. If the above TCP is smallerthan Index_Start_TC of INDEX 2, the operation proceeds to Step S6, wherethe index number is determined to be equal to “1”. If, on the otherhand, it is found in Step S5 that the above TCP is greater thanIndex_Start_TC of INDEX 2, the operation proceeds to Step S7, whereIndex_Start_TC of INDEX 3 of the track number TNO. 1 is compared withthe above TCP. If the above TCP is smaller than Index_Start_TC of INDEX3, the operation proceeds to Step S8, wheere the index number isdetermined to be equal to “2”. If, on the other hand, it is found inStep S7 that the above TCP is greater than Index_Start_TC of INDEX 3,the operation proceeds to Step S9, where Index_Start_TC of INDEX of thetrack number TNO. 1 is compared with the above TCP. If the above TCP issmaller than Index_Start_TC of INDEXM, the operation proceeds to StepS10, where the index number is determined to be equal to “M−1”. If, onthe other hand, it is found in Step S9 that th above TCP is greater thanIndex_Start_TC of INDEXM, the operation proceeds to Step S11, whereIndex_Start_TC of INDEXM of the track number TNO. 1 is compared with theabove TCP. If the above TCP is smaller than Index_Start_TC of INDEXM+1,the operation proceeds to Step S12, where the index number is determinedto be equal to “M”.

Then, the operation returns to Step S2 and if it is found in Step S2that the above TCP is greater than the above TC2, the operation proceedsto Step S2, where Track_Start_Time_Code (TC3) of Track Number (TNO. 3)is compared with the above TCP. If the above TCP is smaller than TC3,the operation proceeds to Step S22, where the current track number TNO.is determined to be equal to “2”. Then, in Step S23, TC2 of the tracknumber TNO. 2 is subtracted from TCP to obtain the elapsed time TCN(minute, second, frame).

After the above Step S23, the operation proceeds to the processingsequence of *2 surrounded by broken lines, where the index number (IDX)in the track number INO. 2 is determined. Since this sequence is similarto that of *1 above, it will not be described here any further.

Then, in Step S31, if the above TCP is smaller than TCN of the tacknumber N (TNO. N), the operation proceeds to Step S32, where the currenttrack number TNO. is determined to be equal to N−1. In Step S33, TC(N−1)of the track number TNO. (N−1) is subtracted from TCP to obtain theelapsed time TCN (minute, second, frame).

After the above Step S33, the operation proceeds to the processingsequence of *N−1 surrounded by broken lines, where the index number(IDX) in the track number TNO. N−1 is determined. Since this sequence issimilar to that of *1 above, it will not be described here any further.

If it is found in Step S31 that the above TCP is greater than the N-thTCN of the track number TNO, the operation proceeds to Step S41, whereTrack_Start_Time_Code (TCN+1) of the track number N+1 (TNO. N+1) iscompared with the above TCP. If it is found that TCP is smaller thanTCN+1, the operation proceeds to Step S42, where the current tracknumber TNO is determined to be equal to “N”. Then, in Step S43, TCN ofthe track number N (TCN. N) is subtracted from TCP to obtain the elapsedtime TCN (minute, second, frame).

After the above Step S43, the operation proceeds to the processingsequence of *N surrounded by broken lines, where the index number (IDX)in the track number TNO. N is determined. Since this sequence is similarto that of *1 above, it will not be described here any further.

Then, in the disk replaying apparatus 1, the sub-dataconverter/generator 9 turns TCP into absolute time TCA as shown in FIG.18, using TCP read out by the additional information detector/processor8 and the table stored in the memory 10 as shown in FIG. 16. Thereafter,the disk replaying apparatus 1 compares the track start time code ofeach track with TCP, starting from the track number TNO. 2. TNO of FIG.17 that is greater than the N-th TC of the track number TNO and smallerthan the N+1-th TC will be equal to N. The value obtained by subtractingthe N-th TC of TNO from TCP represents the elapsed time of the track TCN(minute, second, frame) of FIG. 17. Then, each index start time code ofTNO. N in the index list is compared with TCP to determine the currentindex number (IDX). Thus, Q data as shown in FIG. 17 can be preparedwith the above described flow of operation of conversion/generation.Then, fixed value data such as CONTROL and address ADA shown in FIG. 4are added thereto to produce complete Q data.

If the current absolute time is 7 minute, 40 second, 33 frame in thelist of area TOC shown in FIG. 16, then the track number TNO will be “2”and the elapsed time TCN will be 2 minute, 10 second, frame 33, whereasIDX will be “2”.

Now, the operation of the above embodiment will be described further byreferring to the flow chart of FIG. 18 and also to FIG. 19.

Firstly, TCP “7 minute, 40 second, 33 frame” as read out by theadditional information detector/processor 9 is written into TCA of FIG.17. Then, Track_Start_Time_Code (TC2) “5 minute, 30 second, 00 frame” ofthe track with the track number 2 (TNO.2) is compared with the aboveTCP. Since TCP is greater than TC2, the operation proceeds to Step S21,where Track_Start_Time_Code (TC3) “11 minute, 40 second, 00 frame” ofthe track with the track number 3 (TNO. 3) is compared with the aboveTCP. Since TCP is smaller than TC3, the operation proceeds to Step S22,where the track number TNO is made equal to “2”. Then, in Step S23, TC2is subtracted from TCP to obtain 2 minutes, 10 seconds, 33 frames asTCN, or the elapsed time of the track number 2.

Also, “6 minute, 10 second, 00 frame” of INDEX 2 is compared with theabove TCP and, since TCP is greater of the two, TC “8 minute, 10 second,00 frame” of INDEX 3 is compared with the above TCP. Since TCP issmaller of the two, the index number will be made equal to “2”.

Thus, to convert the additional information read out from the opticaldisk 2 by means of the optical pickup 3 of the disk replaying apparatus1 into data corresponding to Q code of the sub-data of a CD, the data ofthe area TOC is read out by the additional informationdetector/processor 8 firstly when the disk is placed in position andstored in the memory 2. For an ordinary track replaying operation, thetime code in the header is read out by additional informationdetector/processor 8 and converted into channel status data and userdata Q code equivalent to that of CDs by the user dataconverter/generator 9, referring to the information on the track list inthe area TOC data stored in the memory 10.

Thus, the conventional digital recorder that receives the digitalinterface output by way of the output terminal 11 identifies the CDcategory by decoding the channel status data and detects the sub-data ofthe CD including the track number and the elapsed time by decoding the Qcode of the user data. Thus, it automatically records the start Id andthe track number corresponding to the detected data on the recordingmedium to a great advantage for the operation of the digital recorder.

For example, the value obtained by subtracting the start address of theN-th address in the track list from the time code address beingreproduced will correspond to the elapsed time on the track.

Note that channel status data is more often than not uniquely defined bythe category and the parameters of the equipment to be used. Forexample, channel status data can be generated for a new optical disk byfixing the category code to CD, the sampling frequency to 44.1 KHz andthe emphasis to off.

This operation of the present invention will be briefly discussed byreferring to FIG. 10.

Firstly, in Step 101, it is determined if the CD layer or the HD layerof the mounted optical disk that is to be replayed. If is determined inStep 101 that the CD layer is specified by the user for replaying, theoperation proceeds to Step 102, where the TOC area of the CD layer isreplayed firstly to access the program area and retrieve the necessarydata therefrom on the basis of the obtained TOC information. Then, inStep 103, the sub-data annexed to the main data of the digital audiosignal reproduced from the program area in Step 102. If, on the otherhand, it is determined in Step 101 that the HD layer is specified by theuser for replaying, the operation proceeds to Step 105, where the TOCarea of the CD layer is replayed firstly and then in Step 106, the areaTOC information is stored in the memory. In Step 107, the program areais accessed and the necessary data is retrieved therefrom on the basisof the obtained control information on the area TOC. Then, in Step 108,the program number and the passed-by addresses of the program beingreplayed are generated on the basis of the recording addresses expressedin terms of absolute addresses of each program stored in the memory andthe absolute addresses reproduced from said program area.

Thereafter, in Step 109, the first switch and the second switch of FIG.1 are turned to the HD side under the control of the control section.While the flow chart of FIG. 20 is described above in terms of amulti-layer disk, the flow chart applies to the use of a CD and an HDdisk by modifying Step 101 to determine if the CD or the HD disk is tobe replayed.

With the above described method, the additional information of a noveloptical disk can be converted into channel status data and user dataequivalent to those of a CD, which can then be used as digital audiointerface output.

While a multi-bit digital signal of 16 bits with a sampling frequency offs (Hz) conforming to the existing CD standards and output from thedigital interface output section is produced and stored in some otherrecording medium in the above embodiment, it may alternatively be soarranged that a piece of music is divided on the basis of the sub-dataincluding channel status data and user data output from the sub-dataconverter/generator 9 when the 1-bit digital audio signal sampled with asampling frequency of fs multiplied by 64 (64×44.1 KHz=2,8224 MHz) andoutput from the audio signal output section 6 in FIG. 1 is recorded onsome other recording medium.

Thus, according to the present invention, when replaying a disk storingdigital audio signals recorded according to an HD system that isdifferent from the CD system, the additional information including thetrack number and the elapsed time of each piece of music are detectedand converted into data equivalent to channel status data and user dataconforming to the CD standards for the digital audio interface, whichdata are then output to the digital interface output. With thisarrangement, the advantage of automatically recording the start Ids andthe track numbers on the recording medium can also be maid availablewhen recording a digital recorder such as DAT or mini-disk.

What is claimed is:
 1. A disc recording medium having two layers,wherein a first layer comprises: a first program area for recording atleast one program having a program number and a running timecorresponding to each program recorded therein, wherein each program isencoded according to a first format; and a first management area forrecording management data for managing an absolute time corresponding toeach program recorded in said first program area; wherein a second layercomprises: a second program area for recording at least one programhaving only absolute time without a program number and a running time,wherein each program is encoded according to a second format; and asecond management area for recording management data for managing anabsolute start time and for use in calculating a program numbercorresponding to each program in said second program area.
 2. The discrecording medium according to claim 1, wherein said program recorded insaid first program area of said first layer comprises PCM digital audioinformation.
 3. The disc recording medium according to claim 1, whereinsaid program recorded in said second program area of said second layercomprises 1-bit digital audio information.
 4. A disc recording mediumcomprising: a program area for recording therein at least one programand an absolute time without a program number and for recording thereina running time corresponding to each program; and a management area forrecording therein data for managing an absolute start time for eachprogram and for calculating a program number corresponding to eachprogram recorded in the program area.
 5. The disc recording mediumaccording to claim 4, wherein the program is modulated by ΔΣ modulation.